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Machine-learning-inspired SMEFT simplified template cross sections: A case study in ZH production

Daniel Conde, Miguel G. Folgado, and Veronica Sanz

Phys. Rev. D 114, 015037 – Published 24 July, 2026

DOI: https://doi.org/10.1103/4zz1-dv63

Abstract

The simplified template cross section (STXS) program has become the standard interface between Higgs measurements and global fits, but its fixed one-dimensional boundaries are not guaranteed to align with the phase-space directions to which the Standard Model effective field theory (SMEFT) is most sensitive. We propose a machine-learning-inspired extension of STXS in which supervised classifiers are used only at the design stage to identify simple, publishable phase-space boundaries. Using associated Higgs production, pp→ZH, as a case study and a benchmark momentum-dependent bosonic SMEFT deformation, we show that the relevant signal-background separation is well captured by a linear boundary in the (pTZ,mZH) plane. We construct such boundaries with a linear support vector machine and with a deep-neural-network-assisted distillation procedure, and compare them directly with the standard STXS pTZ bins through a common single-region Asimov-significance analysis. In this proof-of-concept setup, the machine-learning-inspired regions systematically outperform the corresponding STXS regions, with the largest gains appearing in the boosted regime where SMEFT effects are concentrated. The final observable remains a simple linear cut, preserving the transparency and experimental portability that make STXS useful.

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